Silver halide photographic paper which produces warm-toned image color and method of making it

ABSTRACT

Process for the manufacture of a silver halide photographic paper which produces warm-toned image of from olive-brown to brown-black when developed and the tone of which is endurable against hot-drying of the finished print by employing two compounds having the following formulae:

United States Patent Yasushi Ohyama Takatsuki-shi; I Kiyoshi Futaki, Kyoto; Senji Tosa, Kyoto; Yaichi lshida, Kyoto, all of Japan lnventors Appl. No. 865,486 Filed Oct. 10, 1969 Patented Oct. 26, 1971 Assignee Mitsubishi Paper Mills, Ltd.

Chiyoda, Tokyo, Japan Priority Oct. 14, 1968 Japan 43/74196 SILVER HALIDE PHOTOGRAPHIC PAPER WHICH PRODUCES WARM-TONED IMAGE COLOR AND METHOD OF MAKING IT 10 Claims, No Drawings Int. Cl G03c l/l0 Field of Search 96/58, 77,

Primary ExaminerJohn T. Goolkasian Assistant ExaminerW. E. Hoag Attorneywaters, Roditi, Schwartz & Nissen mulae:

SILVER HALIDE PHOTOGRAPHIC PAPER WHICH PRODUCES WARM-TONE!) IMAGE COLOR AND METHOD OF MAKING IT The present invention relates to a silver halide photographic paper producing warm-toned image of from olive brown to brown-black endurable against hot-drying and a process for the manufacture thereof.

Some ordinary photographic papers which are manufactured by coating silver halide emulsions onto photographic base papers and used for portrait and salon picture give warmtoned images of olive brown to brown-black when developed. It has generally been considered that when grains of silver halide emulsion are fine, the structure of image silver after developed becomes fine and color tone of image becomes warmer. Accordingly, for the purpose of obtaining fine silver halide grains, namely warmer-toned image of color when developed, a natural restrainer in gelatine has heretofore been utilized. The addition of mercapto-pyrimidines, 6-methyl4- hydroxy-l ,3,3a-7-tetrazaindene or derivatives thereof to gelatine is effective for inhibiting the evolution of fogs but is not so much effective for obtaining the warmer toned image of color when developed.

An application to photographic materials of some compounds (referred to temporarily hereinbelow as N'-R-benzoazoline-2-thiones), represented by the general formula wherein x is o -s N-or CH CH-, R is an alkyl group and R is a lower alkyl, methoxy, ethoxy, halogens or the like, has been reported by the present inventors (for example, Pharmaceutical Bulletin 74 (1954), 1365 and Bulletin of Chemical Society of Japan," 25 (1952), IS). The addition of these N-R'-benzoazoline-2-thiones to emulsions increases development accelerating property and blue-black developing property of the emulsions, but does not almost or utterly exhibit inhibiting property of grain-growth of silver halide and in reverse, rather exhibits grain-growth of aggregation of grains of silver halide. Therefore, these compounds are quite ineffective for the manufacture of emulsion for producing warmer toned image of color.

On the other hand, even though warmer toned image of color is obtained on a print by developing, fixing, washing with water and drying, it is only the case where the drying is carried out by air dry in room, dry air at a relatively lower temperature below 80 C. or by means of a glazing machine. However, when the drying by a hot glazing machine at a higher temperature of 100 C. or more which has recently adopted for the purpose of accelerating the drying of prints, such a tendency is obviously recognized that a beautiful warmer toned image of color obtained immediately after the development is lost to be changed to inferior colder tone. For preventing this phenomenon, it is effective to immerse the prints after the developing treatment into a bath containing special mereapto compounds, for example, 2-mercaptobenzothiazole, 2-mercapto-benzimidazole and the like. However, said treatment means the increase of one step in the operation and moreover, the correct maintenance of concentration of the compound in bath comes into question in the case of mass-treatment.

An object of the present invention is to provide a process for the manufacture of a silver halide photographic paper which produces excellent warm-toned image of from olive brown to brown-black endurable against hot-drying.

Another object of the present invention is to provide a silver halide photographic paper manufactured in accordance with said process.

In accordance with the present invention, it has been found that a silver halide photographic paper capable of producing excellent warm-toned image of from olive brown to brownblack endurable against hot-drying is manufactured by employing adequate amounts of one or more ofN-methyl-benzoazoline-2-thiones or derivatives thereof at the first stage of emulsion-making (the stage of emulsion, precipitation and grain-growth of silv er halide) and employing adequate wherein X is a member selected from the group consisting of O, S-, CH CH- and N(CH R is a member selected from the group consisting of hydrogen (unsubstituted), lower alkyl, mcthoxy, ethoxy and halogens. Since the authorized generic name of said four kinds of compounds is unavailable, the present inventors call it temporarily as N- methyl-benzo azoline-Z-thiones. K

These compounds are employed at the stage of emulsion precipitation and grain-growth of silver halide to restrain appropriately the grain-growth of silver halide and result in the emulsion with narrow grain-size distribution. The developing property of the emulsion seems to be accelerated and when developed, strongly warmer and beautiful toned image of from olive brown to brown-black can be produced. The amount of addition of these compounds is conspicuously concerned with the color tone of image produced and is not constant being dependent not only upon the objective color tone ofimage, sensitivity and gradation but also largely upon the composition of prescription of emulsion and the kind of gelatine used. However, the optimum amount of use thereof is approximately 0.001 to l g. per gram mole of silver halide. The practical amount used may be appropriately adjusted in accordance with the purpose, condition and the like.

The time of addition of these compounds is generally effective not only at the first stage of emulsion precipitation but also at the later stage of said precipitation so far as the period of grain-growth of silver halide is long. On the contrary, how ever, the addition to the emulsion which is completely ripened is scarcely effective and in reverse, brings about colder tone of image of blue-black in some cases.

In addition, since these compounds have in themselves a property as a certain sulfur-sensitizers, the addition of the present compounds results in relatively easy sensitization of emulsion for its grain-size and tone of image produced. ln this point, the present compounds are largely different from the prior grain-growth inhibitors.

The emulsion applicable to the present invention may be a low speed chloro-bromide' emulsion which has heretofore been widely used for contact papers for portrait without any special contrivance in the prescription so far as the prescription contains the ordinary gelatine and is able to prepare an emulsion which produces somewhat warmer tone of image when developed. In addition, it may of course be better to alter the prescription of emulsion so as to make it adaptable to the present object. Also, there may be used an emulsion having high speed in such a degree as to be used for enlargement, namely an emulsion having essentially somewhat coarser grains. Further, it is preferable not to add formalin in an amount beyonu the necessity. Excessive formalin acts to a binder such as gelatine and the like in the course of storage of photographic paper manufactured and markedly impairs color tone of image when theprint is developed.

The l,5-disubstituted-S-triazolidino (l,2a)-S-triazolidine- 3,7-dithiones referred to in the present invention have the general formula wherein R is an lower alkyl group having 4 or more carbon atoms, phenyl group or substituted phenyl group.

These compoiTrfis inelude l,idiphenyl-S-triazolidino l ,2a)-S-triazolidine-3,7-dithione, l,S-diheptyl-S-triazolidino l,2a)-S-triazolidine-3,7-dithione, l,5-dipentyl-S-triazolidino l,2a)-S-triazolidine-3,7-dithione and 1,5-dihexyl-S- triazolidino l ,2a)-S-triazolidine'-3 ,7-dithione.

These compounds are employed in an amount of 0.001 to l g. per gram mole of silver halide at the last stage of emulsionmaking before coating on a base paper as an additive for the emulsion for the purpose of not impairing the color tone of image to be developed to change it into warmer tone of image of from olive brown to brown-black and preventing inferior colder toning thereof by rapid hot-drying at the time of finishing prints. The amount within said range may beselected freely in accordance with the existence of other additives and the kind of emulsions.

Further, usual additives before coating such.as hardeners, surface active agents and the like, antifoggants, stabilizers, optical sensitizers, fluorescent brighteners and the like may be added to the emulsion in the usual manner.

Base papers to be used in the present process include baryta papers, raw papers not barytaged, polyethylene-coated papers and the like, These base papers are preferred not to contain formalin.

The present invention will further be explained in detail with reference to the following examples. But the present invention is of course not limited to this scope.

EXAMPLE 1 A low speed photographic paper which produces-excellent warm-toned image of olive brown is manufactured from the following prescription:

(A) Solution Water 400 ml. Gelatine l g. Citric acid 0.4 g. 1% Ethanol solution of N,Nf-Dimethyl-benzimidazolinc-Z- thione 4.0 ml. (B) Solution (50C.)

Silver nitrate 20.0 g. Water 100 ml. (C) Solution (about 45 C.)

Sodium chloride 9t0 g. Potassium bromide L0 Citric acid 0.8 g. Water l00 ml. (D) Solution (50 C.)

Gelatine 50 g. Citric acid 0.4 g. Water 300 ml. (E) Solution (50 C.) Gelatine 60 g. Water 7 400 ml. (F) Solution (normal temperature) a 1% solution of l,5-diphenyl-S-triazolidino-S-triazolidine-Ilfldithione 2.0 ml. 1% solution of 2-merca pto-benzo thiazole 1.0 ml. Ethanol 40 ml. solution of chrome alum 40 ml. [0% solution of formalin l0 ml. 3% solution of saponin 60 ml. Water 80 ml. Rice starch (as matte powder) l0 g.

(A) solution was added with (B) solution while maintaining at 50 C. with stirring and after leaving the mixed solution at 50 C. for 1 minute, (C) solution was added thereto at a time so as to prepare the temperature after mixing at 50 C. After additional one minute, (D) solution was added to the resultant mixture to ripen at 50 C. for 40 to 50 minutes (the time of ripening is to be controlled depending upon the kind of gelatine used and the gradation desired). Subsequently, adding (E) solution to the mixed solution to further ripen for 10 to 20 minutes, and then chilling the resultant mixture, there was accomplished the emulsion. Finally, adding (F) solution as an additive before coating to the emulsion to prepare the total weight of 1.5 Kg, coating the resultant emulsion onto an ordinary baryta paper in a thickness of the order of g./m and drying the resultant paper, there was obtained a photographic paper. After exposed, developing the photographic paper by the ordinary developer such as methol-hydroquinone or phenydonehydroquinone, there was obtained a print of beautiful warmer toned image of olive brown which was not changed to colder tone or brown color even treated with a grazing machine.

On the contrary, however, in the case of a photographic paper which was manufactured by excluding l,5-diphenyl-S- triazolidino-S-triazolidine-3,7-dithione of the present invention from (F) solution, it was recognized that a tone of image of the print produced therefrom was considerably changed from olive brown to the side of brownblack. And, in the case of a photographic paper which was manufactured by further excluding 2-mercapto-benzothiazole' from said (F) solution, it was recognized that a print which was dried at a lower temperature, for example, being dried in room, after the development showed a beautiful tone of image of olive brown but a print which was hot-dried was changed in a tone of image to a cold tone approximately near neutral black.

EXAMPLE 2 Since the photographic paper manufactured in example l uses formalin as a hardener, there is a tendency of losing a beautiful tone of image when developed in,the case of being left before use at normal temperature (in particular, in tropical zone and in summer) and the effect of the present invention cannot be maintained for a long period of time.

Using 200 ml. of 5 percent solution of starch monomaleate having one substitution per glucose unit which was obtained from a soluble starch in place of 5 percent solution of starch and a baryta paper free from formalin or both-sides polyethylene coated paper as the base paper, there was obtained a photographic paper which sufficiently exhibits the effect of the present invention without losing excellent tone of image produced immediately after the development even stored overone year from the manufacture.

EXAMPLE 3 ,Treating in the same manner as in example I except for the combined use of 1.5 ml. of 1 percent solution ofN-methyll ,2-

dihydroquinoline-Z-thione with 1.0 ml. of l percent solution EXAMPLES 4 and 5 Adding to (D) solutionthe additive which was added to (A) solution of example 1, there was obtained a photographic paper for portrait which easily produces relatively soft tone and excellent tone of image. Said fact will probably be due to the reason that, since the growth of silver halide grains is inhibitated after the grains are grown up to some extents, the distribution of grain-sizes is liable to become wider as compared with the addition to (A) solution.

Similarly, a portion or whole of the additive could be added to (E) solution.

These modifications may be applicable in accordance with slight variation in property of gelatine used and in the prescription of emulsion, and may be operable for those skilled in the art in determining the prescription of emulsion within the scope and spirit of the present invention.

EXAMPLE 6 The following prescription is an example for a medium speed chlorobromide paper for projection printing which produces excellent warmer tone of image. It is obvious that the same may be varied in many ways in accordance with the variation of prescription and the selection of gelatine.

(A) solution (65 C.)

Water 300 ml.

Gelatine g. Sodium chloride 9 g. Potassium bromide 8.7 g. Cadmium chloride 0.5 g. Citric acid 0.2 g (B) solution (about 60 C.)

Silver nitrate 25.0 g. Water 250 ml. (C) solution (65 C.)

Gelatine 65 g. Water 250 ml. 1% solution ofN,N-dimethyl-S-methoxy-benzimi-dazoline-Z -thione 3.0 ml. 1% solution ofN-methyl-6-methyl-benzoxaloline-2-thione 2.0 ml (D) solution Gelatinc (solid) 25 g. (E) solution (normal temperature) 0.1% solution of yellow colored eyanine dye (sensitizing maximum: 4700 A.) 5.0 ml. 1% solution of 1,S-dipentyl-S-triazolidino-S-triazo1idine' 3,7dithione 3.0 ml. Ethanol 50 mlv 1% solution of 5,6-tetramethylene-4-hydroxy-1,3,3

a,7tetrazaindene 1.0 ml. 5% solution of saponin 25 ml. 2% solution of chrome alum 50 ml. 10% solution of formalin 10 ml.

Water 100 ml. Fine powdered silica (marketed sy1oid 0308) 10 g.

(B) solution was charged into (A) solution at a time and after 30 seconds, (C) solution was added to the resultant mixed solution to ripen at 65 C. for 60 to 90 minutes (the time of ripening is to be controlled depending upon the kind of gelatine used and the desired speed and gradation). After ripening, the resultant emulsion was chilled and set with the addition of solid gelatine of (D), washed with water and stored in an icebox. Before coating, the resultant emulsion was heated to dissolve at 40 C and added with (E) solution to make up the total weight of 1.5 Kg. The resultant emulsion was coated on a baryta paper in a thickness of about 150 ,g./m. and dried.

Thus,-there was obtained the photographic paper which has enough sensitivity suitable for projection printing and produces a beautiful warmer tone of image of newly fashioned brown-black. The color tone of image was not changed even drying rapidly the print by the use of a hot-glazing machine.

In the case where the present compound in (E) solution was removed from the prescription, it was recognized that the color tone of image was changed to colder tone at the time of drying the print by a hot-glazing machine. And, in the case where the present compounds in (C) solution was further-additionally removed therefrom, the restraining property of gelatine used was low and consequently, there was obtained the print of from pure black to blue-black as in the conventional photographic paper for projection printing.

From the above results, the effect of the present compounds is obvious.

EXAMPLE 7 Adding first (C) solution to (A) solution and then adding (B) solution to the resultant mixture in the procedure of example 6, there was obtained a photographic paper which has considerably low sensitivity as compared with that of example 6 but produces a conspicuously olive-rich tone of image. Therefore, the paper is more suitable for a photographic paper for portrait as well as for contact-printing and projectionprinting.

What is claimed is:

1. A process for the manufacture of a silver halide photographic paper with wann-toned image color durable against hot-drying, which comprises adding at least one of the derivatives of N-methyl-benzo-azole-2-thiones having the general formula (1),

R C=S on, (I) wherein X is a member selected from the group consisting of -O-, -S, CH CH- and N(CH and R is hydrogen (unsubstituted), or a member selected from the group consisting of lower alkyls, methoxy, ethoxy and halogens, at the first stage of emulsion making (precipitation and grain-growth), and further adding at least one of 1,5-disubstituted-S-triazolidino( l,2a)-S-triazo1idine-3 ,7-dithiones having the general formula (11) S g HN I NH H it wherein R is a member selected from the group consisting of lower alkyl groups containing 4 or more carbon atoms, phenyl group and substituted phenyl groups added to the emulsion at the last stage of emulsion making before coating of the finished emulsion on a base paper.

2. A silver halide photographic paper with warm-toned image color endurable against hot-drying, manufactured by a process according to claim I.

3. A process for the manufacture of a silver halide photographic paper according to claim 1, wherein N-methyl-bcnaoxazoline-Z-thione or the derivatives of it is used at the first stage ofemulsion making.

4. A process for the manufacture of a silver halide photographic paper according to claim 1, wherein N-methylbenzothia zoline-2-thione or the derivatives of it is used at the first stage of emulsion making.

5. A process for the manufacture of a silver halide photographic paper according to claim 1, wherein N,N'-dimethylbenzimidazoline-Z-thione or the derivatives of it is used at the first stage of emulsion making.

6. A process of the manufacture of a silver halide photographic paper according to claim 1, wherein N-methyll,2- dihydroquinoline-2-thione or the derivatives of it is added to the emulsion at the first stage of emulsion making.

7. A process of the manufacture of a silver halide photographic paper according to claim 1, wherein 1,5-diphenyl-S- triazolidino( l,2a-S-triazolidine-3,7-dithione is added to the emulsion at the last stage of emulsion making.

. 8. A process of the manufacture of a silver halide photographic paper according to claim 1, wherein 1,5-diheptyl-S- triazolidino(l,2a-S-triazolidine-3,7-dithione is added to the emulsion at the last stage of emulsion making.

9. A process of the manufacture of a silver halide photographic paper according to claim 1, wherein 1,5-dipentyl-S- triazolidino(l,2a-S-triazolidine-3,Tdithione is added to the emulsion at the last stage of emulsion making.

10. A process for the manufacture of a silver halide photographic paper according to claim 1, wherein 1,5-dihexyl-S- triazolidino(l,Za-S-triazolidine-3,7-dithione is added to the emulsion at the last stage of emulsion making. 

2. A silver halide photographic paper with warm-toned image color endurable against hot-drying, manufactured by a process according to claim
 1. 3. A process for the manufacture of a silver halide photographic paper according to claim 1, wherein N-methyl benzoxazoline-2-thione or the derivatives of it is used at the first stage of emulsion making.
 4. A process for the manufacture of a silver halide photographic paper according to claim 1, wherein N-methyl-benzothiazoline-2-thione or the derivatives of it is used at the first stage of emulsion making.
 5. A process for the manufacture of a silver halide photographic paper according to claim 1, wherein N,N''-dimethyl-benzimidazoline-2-thione or the derivatives of it is used at the first stage of emulsion making.
 6. A process of the manufacture of a silver halide photographic paper according to claim 1, wherein N-methyl-1,2-dihydroquinoline-2-thione or the derivatives of it is added to the emulsion at the first stage of emulsion making.
 7. A process of the manufacture of a silver halide photographic paper according to claim 1, wherein 1,5-diphenyl-S-triazolidino(1,2a)-S-triazolidine-3,7-dithione is added to the emulsion at the last stage of emulsion making.
 8. A process of the manufacture of a silver halide photographic paper according to claim 1, wherein 1,5-diheptyl-S-triazolidino(1,2a)-S-triazolidine-3,7-dithione is added to the emulsion at the last stage of emulsion making.
 9. A process of the manufacture of a silver halide photographic paper according to claim 1, wherein 1,5-dipentyl-S-triazolidino(1,2a)-S-triazolidine-3,7-dithione is added to the emulsion at the last stage of emulsion making.
 10. A process for the manufacture of a silver halide photographic paper according to claim 1, wherein 1,5-dihexyl-S-triazolidino(1,2a)-S-triazolidine-3,7-dithione is added to the emulsion at the last stage of emulsion making. 